The present invention relates to a reclining device applied to a seat of a vehicle, such as an automobile, or of a piece of furniture, and more particularly to an improvement of locking means of the reclining device.
A seat of an automobile or the like is provided with a reclining device for adjusting the in clination of seat back. There are various types of conventional reclining devices. Described in U.S. Pat. No. 5,778,733 is one such reclining device that uses a linear mechanical lock system, combining a lead screw and a nut.
The reclining device using the linear mechanical lock system comprises a housing fixed to a seat cushion of a seat or the like, the lead screw connected to a seat back of the seat, etc. Further, the nut is rotatably stored in the housing. The nut is in mesh with the lead screw. In this prior art example, the nut is unlocked in changing the angle (reclining angle) of the seat back. If the inclination of the seat back is changed in this unlock state, the lead screw moves in its axial direction with the change of the seat back angle, and the nut rotates in the housing. The seat back can be locked by locking the nut after adjusting the reclining angle.
In the prior art example, the lead angle of the lead screw must be made wider than that of an ordinary screw, in order to allow the nut to rotate as the lead screw moves in the axial direction after the nut is unlocked. In order to reduce the resistance of rolling friction of the nut on the lead screw, moreover, a bearing member should be interposed between the housing and the nut. Further, a lock system is needed to stop the rotation of the nut. In consequence, the conventional reclining device has a complicated construction and requires use of a lot of components, thus entailing an increase in cost.